Back pain afflicts over 75% of Americans during their lifetime and 2% of the American work force suffers a back injury on the job each year. Spinal fusion is the orthopedic procedure routinely used to treat back pain in patients suffering from degenerative disc disease, spinal stenosis, scoliosis, and spinal fracture; however, procedure failure rates range between 5 to 44% and the success rates have not changed significantly over the past 20 years despite increased use of mechanical fixation devices. Regenerative medicine offers a novel approach to this problem by combining osteoinductive biomaterials and environmental cues with osteogenic cells to improve and accelerate the fusion process by promoting ectopic new bone formation. So far, this technology has been limited by the availability of "off the shelf osteogenic stem cells. Cognate Therapeutics holds unique intellectual property and expertise in the isolation, culture, and differentiation of adult stem cells from subcutaneous adipose tissue. We have shown that these Adipose Derived Adult Stem (ADAS) cells display osteoblast potential both in vitro and in vivo. With this scientific background, we postulate: (A) That ADAS cells are osteogenic in vivo and, in combination with a suitable biomaterial carrier, will improve and accelerate spinal fusion in animal models and; (B) That ADAS cells can be transplanted allogeneically with a biomaterial scaffold to achieve a superior spinal fusion as compared to a biomaterial scaffold alone. This Phase I STTR tests these inter-related hypotheses with the following Specific Aims: Aim 1. To determine the effect of syngeneic (Fischer rat derived) ADAS cells on spinal fusion in a rat model. An intertransverse spinal arthrodesis (L4 and L5) will be used to evaluate the osteogenic ability of syngeneic (Fischer rat derived) subcutaneous ADAS cells to promote spinal fusion. Aim 2. To determine the effect of allogeneic (ACI rat derived) ADAS cells on spinal fusion in the Fischer rat model as outlined in Aim 1. Aim 3. To compare and contrast the relative effectiveness of syngeneic and allogeneic ADAS cells in a spinal fusion model. The results of these Phase I studies will provide the basis for an expanded spinal fusion analysis in a large animal model in a future Phase II STTR from the investigators. The availability of "off the shelf ADAS cells for clinical orthopedic procedures will have a significant commercial and therapeutic impact.